I have been using a cast iron skillet and a griddle....and a baking dutch for long time....longer than I have been married...26+....some cast ware isn't machined smooth on the inside....that could be an issue....and does effect cooking/cleaning/seasoning.
Like some of the other posts, I don't always oil....but always clean and dry. I have a good friend with a really old, well seasoned deep skillet. His pan is black with seasoned age. It got that way by not having been heavily scrubbed and always used for deep-fry type cooking. I have never seen a better seasoned pot. Take good care of your cast ware and it will serve you well....don't cook tomatoes in it!! Find an old smoothie if your's has a sand-cast interior. ras